1. Field of the Invention
The present invention relates to a control system for an internal combustion engine capable of switching combustion modes which are different in injection timing, such as a homogeneous combustion mode and a stratified combustion mode, while performing quick-response torque correction by using different manipulated variables according to the combustion modes.
2. Description of the Related Art
For stabilization control of engine speed at idling, load compensation control, and torque control for meeting various requests during running, it has heretofore been practiced to perform torque correction by using manipulated variables which are higher in responsiveness than intake air quantity. Such torque correction is herein referred to as "quick-response torque correction".
On the other hand, in recent years direct-injection spark ignition internal combustion engines have attracted public attention. Typical one of such engines performs, in accordance with an engine operating condition, switching of two combustion modes, i.e., a homogeneous combustion mode in which fuel is injected during intake stroke and is dispersed within a combustion chamber to form a homogeneous mixture, and a stratified combustion mode in which fuel is injected during compression stroke to form a stratified mixture which is concentrated around a spark plug, as disclosed in Japanese patent provisional publication No. 59-37236.